HUUM Hive Heat LS 12 Sauna Stove with Firebox ExtensionThe firebox extension on the HUUM HIVE Heat 12 LS allows loading from another rooms so you don't need to store wood in your sauna. HIVE Heat 12 LS is a highly efficient wood fired sauna heater for smaller saunas. It has a unique structure where fresh air is conducted into the burning process from above to create a strong flame. This allows the burning to be very clean and makes sure that all the wood gets burned and no wood gas escapes the chimney and